Honda Insight Tail Extension Project

[Weather Spotter]

This might have been covered, but what thickens is the foam? Your project is making me think over how I might make a tail for my car. I can not seem to find anything over 1" think and that is blue Dow board. I do not think that will work well.

[Varn]

One inch board can work well. If you really in your heart think that you need more than that you can always use a bit of epoxy and micro and glue two or more boards) boards together. Blue board is about the same as pink board.

I have used two part foam as a glue to put two boards together. It is very sticky.

You can always try to make a metal frame and cover it with polyester fabric,$1 a yard on ebay. Heat will shrink it if needed.

[3-Wheeler]

Originally Posted by Weather Spotter

This might have been covered, but what thickens is the foam?

I normally do not use an expanding foam, like Great Stuff Foam. Why? I have noticed that this foam continues to expand for some time. It was used in the areas of the old motorcycle fairing, and in the hot, summer sun, areas of the fairing bubbled slightly and distorted the paint job.

Now I use expanding foam in areas where if it does expand slightly later on, does make much difference.

Originally Posted by Weather Spotter

...I can not seem to find anything over 1" think and that is blue Dow board....

The foam I used was Owens Corning Foamular, found at Home Depot. A 2" thick, 8Ft board was about $20, and this is half price compared to the blue board that was used on the motorcycle fairing over 15 years ago, so the price has come down over the years.

Originally Posted by Weather Spotter

... I do not think that will work well....

It really depends on how you design it.

But the two inch board is actually 4 times stronger in bending strength compared to the 1" board, and the two inch board is only slightly heavier than the 1" board after glassing both sides, and is much stronger and resistive to bending forces.

The objective of a composite is to simply have the filler material (foam) hold the two outer layers apart (fiberglass) at a constant thickness. Some people claim you can lighten your composite even more by removing part of the foam core when finished, but I think that the foam adds so little to the weight to leave it intact after completion.

I have had issues glueing two thinner boards together to make a thicker board, so maybe my technique is not the best, but I use a thin layer of resin to bond them together, after sanding both surfaces to clear-off the shiny finish. The subpar adhesion has shown up where the two layers get sanded down and "feathered", and then I discover that the bonding process is suspect.

I have not tried expanding foam to bond the two together as it needs air exposure to expand, and there is no air between the two boards to allow this to happen properly. If there is air, then there are also air gaps, and that is not good regarding mechanical strength.

Jim.

[jime57]

Originally Posted by 3-Wheeler

As you can see, I'm ready for some nice R&R.

Jim.

As you well deserve!

[Varn]

There is a two part foam that comes in two cans. One is the resin and the other is the hardener. It hardens well not like the spray can stuff.

It is an excellent adhesive and sands about the same as the pink or blue stuff.

Liquid Foam from Aircraft Spruce

[3-Wheeler]

Originally Posted by Varn

There is a two part foam that comes in two cans. One is the resin and the other is the hardener. It hardens well not like the spray can stuff.

It is an excellent adhesive and sands about the same as the pink or blue stuff.

Liquid Foam from Aircraft Spruce

Varn

Is that two-part foam anything like Gorilla Glue as far as density when it sets up? Or is it more like the stuff that's shot into walls for insulation?

Thanks, Jim.

[retepsnikrep]

Really excellent effort looking forward to some more pics, especially painted and attached.

[Varn]

It is more like pink board Jim, rigid and somewhat brittle. I have not had it set up foamy like the spray foam. I have never used gorilla glue nor tested the stuff in walls. If you are have an alternative way of creating space filling then stick with it. I have used it successfully.

Originally Posted by 3-Wheeler

Varn

Is that two-part foam anything like Gorilla Glue as far as density when it sets up? Or is it more like the stuff that's shot into walls for insulation?

Thanks, Jim.

[jime57]

Originally Posted by 3-Wheeler

I have had issues glueing two thinner boards together to make a thicker board, so maybe my technique is not the best, but I use a thin layer of resin to bond them together, after sanding both surfaces to clear-off the shiny finish. The subpar adhesion has shown up where the two layers get sanded down and "feathered", and then I discover that the bonding process is suspect.

Jim.

Jim, just a thought. Perhaps it would be easier and produce a better final smoothness to conceed some roughness in the fiberglass layer and then smooth with Bondo. From my experience with "shade tree" repairs of race cars, Bondo works easily and produces very smooth finishes - when done correctly. It also adhers tightly to fiberglass. You can create a very nice smoothing tool by wrapping an 8.5x11 piece of sandpaper around a finished 1x4 piece of wood (actually 3.5X.75 finished) and stapleing along an edge. The long length prevents dips in the finish and acts like a plane tool. Since you are using very little Bondo, the weight addition is minimal.

Since the Bondo would be completely sealed from the back, you would not experience the bubbling sometimes seen on normal fender or rust repairs.

Jim E.

[3-Wheeler]

Originally Posted by jimepting

Jim, just a thought. Perhaps it would be easier and produce a better final smoothness to conceed some roughness in the fiberglass layer and then smooth with Bondo. From my experience with "shade tree" repairs of race cars, Bondo works easily and produces very smooth finishes - when done correctly. It also adhers tightly to fiberglass. You can create a very nice smoothing tool by wrapping an 8.5x11 piece of sandpaper around a finished 1x4 piece of wood (actually 3.5X.75 finished) and stapleing along an edge. The long length prevents dips in the finish and acts like a plane tool. Since you are using very little Bondo, the weight addition is minimal.

Since the Bondo would be completely sealed from the back, you would not experience the bubbling sometimes seen on normal fender or rust repairs.

Jim E.

Hi Jim,

You mean like this?

We must be on the same wavelength or something.

There's actually two full size tubes of the stuff on the top and sides right now, and I picked three more tubes that will be used before it gets too cold.





The underside of the extension was fiberglassed this last weekend.



Jim.